The present invention concerns a device to apply paraffin oil to textile threads (whether they be yarns obtained from tuft textile fibers, or continuous synthetic filaments) and it relates, in particular, to a device for applying paraffin oil to weft threads fed to textile machines, as weaving looms.
Applying paraffin oil to textile threads in a known and fairly widespread practice in spinning, which generally consists in causing the thread--before it is wound into cops or reels--to skim over a disk or block of paraffin wax. This operation increases the smoothness of the threads, reducing the friction factor.
In weaving, owing to the ever increasing speed of shuttleless looms which characterizes modern technique, it appears more and more helpful, and sometimes necessary, to treat weft threads with paraffin oil. Particularly in air jet looms, paraffin makes it easier for the thread to be blown across the warp shed and helps to keep it properly stretched out in the fluid stream, reducing the risk of loops or snarls.
In some cases, it is merely sufficient to eliminate the irregularities, deriving from previous treatments on the thread, by means of lubricants, antistatics or other chemical ingredients, which irregularities can either show up when passing from one cop or reel to the other, or even be present in the single cop or reels.
This type of inconvenience can occur quite frequently with acetate viscose rayon yarns: small residues of acetone left on the fiber may cause the lubricant applied on the thread to volatilize from the outer-most layers of the cop and from its ends. Hence, especially if the lubricant is light, i.e. of low molecular weight, there can be great differences in thread behaviour during weft insertion from a same cop, and thus serious difficulties of loom working.
In such cases, a valid remedy can be to apply small quantities of paraffin on the thread. It is a known practice to cause the thread, being unwound from the reel, to skim the surface of a wax block or disk--which may be fixed or even rotary--positioned between the reel and the weft feeder.
This system, though having the advantage of being remarkably simple, however involves different drawbacks. In fact, the spreading of paraffin over the thread, by causing this latter to skim the surface of a block or disk, rarely turns out to be uniform and satisfactory. Furthermore, the typical movement of the weft yarn--intermittent and with variable speed-easily produces on the wax block grooves and irregularities which, due to the same movement, may cause breaking of the yarn. There can be problems also in choosing the wax composition which is most suited to the type of yarn and of fiber being treated; and furthermore, the chemical-physical characteristics of the waxes may be inadequate for launching the yarn in air jet looms.
These difficulties may be largely overcome by using, instead of wax, liquid paraffin oils which allow the addition of emulsifying agents and/or antistatics and which help to make for important characteristics, as viscosity, by mixing different oils.
The devices for applying liquid paraffin, known up to date, consist of a container for the liquid and of a rove or felt strip of textile material which draws by capillarity the oil from the container and spreads it, through direct contact, over the external part of the moving thread.
Various drawbacks are however still present in devices of this type: for example, the difficulty in proportioning the oil and, thus, an uneven distribution of the oil over the thread; the risk that the thread might get caught on the hairy surface of the rove and thus break; and the fast wear of the rove, especially when working yarns or filaments of synthetic fibers.